Weigh or measure your sugar into a bowl and set aside.
In a food processor (I use a Breville Sous Chef Food Processor), pulse the almond paste till it looks like sand on a beach. Add half of the sugar and pulse a couple of times, then add the 2nd half and pulse till all the sugar has incorporated into the almond paste.
Beat the three egg whites for about 3 minutes on high with an (I use a KitchenAid) stand or hand-held mixer. You want the peaks to be firm and not soft. Once it has gotten to that stage, fold in the broken-up almond paste into the firm egg whites. Make sure it is all blended. Loosely cover the bowl with plastic wrap and put it into the refrigerator for at least 1 hour to 1-½ hours.
Preheat oven to 325° and line 2 pans with parchment paper or a silicone sheet and set aside. You can take a teaspoon and drop the dough onto the parchment paper or silicone sheet, but I prefer to use an OXO Good Grips Cookie Scoop, Small to get the same size mounds that bake evenly. Place a couple of almond slices on top of each cookie before going into the oven.
Bake at 325° for 14 to 15 minutes they should start to look a pale brown around the top edges of the cookie. After pulling out from the oven, leave on the baking sheet for a good 5 minutes before moving to the cooling rack.
Put the bittersweet chocolate chips into a microwave dish and melt the chips to the consistency that the chips can be stirred. I did it for about 30 seconds and stirred then heated for about another 20 to 30 seconds.
My Breville Sous Chef Food Processor comes with a small bowl in the bigger bowl so I took some of the almond slices and pulsed them till crushed. I put them in a bowl.
I took a spoon and drizzled the chocolate over the top of a cookie then turned the cookie over and gently pressed the top of the cookie into the bowl of crushed almonds. Just so some of the crushed almonds stuck to the chocolate. Do this to each cookie. Take your cookie sheet pans and line them with parchment paper and put the cookies on the sheet then put into the refrigerator to harden the chocolate.